This invention relates to new .gamma.-butyrolactone derivatives, namely .alpha.-mercaptomethyl-.gamma.-butyrolactone derivatives, to process for preparing the same and to immunomodulating compositions containing the same as an active ingredient.
As a therapeutic agent against rheumatoid arthritis, one of representative autoimmune diseases, there are roughly classified into an anti-inflammatory agent and an immunomodulating agent. The former is a palliative agent and can not be an agent for complete recovery. On the other hand, the latter has been given attention for last several years as a therapeutic agent based on etiology. As such an immunomodulating agent, there have been proposed a gold preparation, D-penicillamine, levamisole, N-(2-carboxyphenyl)-4-chloroanthranilic acid disodium salt (CCA) and the like. However, such drugs show a strong toxicity to a living body and hence it is the present status that a satisfactory therapeutic agent has not yet been developed. Moreover, as sulfur-containing .gamma.-butyrolactone analogous compounds, there have been reported those compounds represented by the formulae ##STR3## and the like in literatures [Ark. Kemi., 26 (10), 111 (1966); Tetrahedron Letters, 1976 (49), 4459; Tetrahedron Letters, 1973 (39), 3831; J. Org. Chem., 40 (8), 1181 (1975); J. Med. Chem., 21 (8), 815 (1978); Biochim. Biophys. Acta., 100 (1), 104 (1965)]; However, they did not at all disclose an immunomodulating activity.